Rotary electric machine stator and method of manufacturing the same

ABSTRACT

A rotary electric machine stator includes a stator core having plural slots and a stator winding that is composed of plural conductor segments. Each conductor segment has a straight portion disposed in the slot and connection ends projecting from the slots and welded to another. The connection ends to be welded cross each other at an angle larger than zero degree.

CROSS REFERENCE TO RELATED APPLICATION

[0001] The present application is based on and claims priority fromJapanese Patent Application 2002-53114, filed Feb. 28, 2002, thecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a stator of a rotary electricmachine to be mounted in a vehicle such as a passenger car or a truckand a method of manufacturing such a stator.

[0004] 2. Description of the Related Art

[0005] As the output power of the vehicle generators has been increasingin order to operate various vehicle safety devices. It is well knownthat the output power of a vehicle ac generator can be increased if thespace factor of a stator winding to stator core's slots is increased,which reduces the resistance of the stator winding. The space factor canbe increased if the conductors or wires of the stator winding insertedin the slots are snugly fitted to the slots.

[0006] For example, Japanese Patents P3196738, P3104700 and JapanesePatent Application Publication P2001-197709, or their corresponding U.S.patent application Publication US2002/0053126A1, U.S. Pat. No.6,403,921B1 and U.S. patent application Publication 2001/0007169A1,disclose methods of manufacturing a stator.

[0007]FIG. 14 shows one of the methods disclosed in the above-statedpublications. As shown in FIG. 14, a plurality of U-shaped conductorsegments 404 is inserted into slots of a stator core 400, and theconductor segments 404 are bent to incline in the circumferentialdirection while connection ends 406 of the conductor segments 404 areclamped. Thereafter, the connection ends 406 are welded together by anarc welder to form a stator winding.

[0008] When a stator is manufactured by the above-described method, theconnection ends 406 have to have a certain length of axially extendingstraight portion, which increases useless axial size of the stator.

SUMMARY OF THE INVENTION

[0009] The invention is to provide a rotary electric machine stator inwhich the above axially extending straight portions to be welded areomitted or reduced.

[0010] According to a feature of the invention, a pair of connectionends of conductor segments, which are connected together to form astator winding of a stator, cross each other at an angle larger thanzero degree.

[0011] Each connection end may have a side surface in contact with aside surface of another connection end to be connected together.However, the connection ends may be connected together at a side surfaceof one connection end and a top surface of another connection end.

[0012] Preferably, one of a pair of conductor segments whose connectionends are welded is disposed adjacent the other conductor segment in aradial direction of the stator and is bent in a circumferentialdirection of the stator that is opposite to the other conductor segment.

[0013] It is another object of the invention is to provide a method ofmanufacturing a rotary electric machine stator that has the above-statedfeatures. Such a method includes a step of inserting straight portionsof conductor segments into a plurality of slots of a stator core, a stepof bending the conductor segments so that connection ends of theconductor segments that are disposed adjacent to each other in a radialdirection can incline in opposite circumferential directions to crossone another, and a step of welding pairs of the connection ends crossingeach other.

[0014] Preferably, the step of bending includes a step of attaching abending tool to a side surface of the conductor segments and a step ofturning the bending tool about a position near one of the slots.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Other objects, features and characteristics of the presentinvention as well as the functions of related parts of the presentinvention will become clear from a study of the following detaileddescription, the appended claims and the drawings. In the drawings:

[0016]FIG. 1 is a cross-sectional side view of a vehicle ac generatorthat includes a stator according to a preferred embodiment of theinvention;

[0017]FIG. 2 is a fragmentary cross-sectional view of a portion of thestator having slots in which straight portions of conductor segments areinserted;

[0018]FIG. 3 is a perspective view of a pair of U-shaped conductorsegments;

[0019]FIG. 4 is a fragmentary side view of the stator;

[0020]FIG. 5 is a top view of the stator winding;

[0021]FIG. 6 illustrates a step of bending the conductor segments;

[0022]FIG. 7 illustrates a step of bending the conductor segments;

[0023]FIG. 8 illustrates a step of bending the conductor segments;

[0024]FIG. 9 illustrates a step of bending the conductor segments;

[0025]FIG. 10 illustrates a step of bending the conductor segments;

[0026]FIG. 11 illustrates a step of bending the conductor segments;

[0027]FIG. 12 is a fragmentary side view of connection portions of theconductor segments of a variation of the stator according to thepreferred embodiment;

[0028]FIG. 13 is a fragmentary top view of connection portions of theconductor segments of the variation; and

[0029]FIG. 14 is a perspective view of a prior art stator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] A method of manufacturing stator winding of a rotary electricmachine stator according to a preferred embodiment of the invention willbe described with reference to the appended drawings.

[0031] As shown in FIG. 1, a vehicle ac generator 1 according to thepreferred embodiment of the invention includes a stator 2, a rotor 3, ahousing 4, a rectifier unit 5 and others.

[0032] The rotor 3 functions as a magnetic field generator and rotatestogether with a shaft 6. The rotor 3 includes a pole core unit 7, afield coil 8, a pair of slip rings 9, 10, a mixed flow fan 11 and acentrifugal fan 12. The shaft 6 carries a pulley 20 that is rotated byan engine via a belt. The pole core unit 7 has twelve claw-shapedmagnetic poles 73 and is composed of a pair of pole core members. Eachpole core member has a boss portion 71, a disk portion 72 and sixclaw-shaped magnetic poles 73.

[0033] The mixed flow fan 11 is fixed by welding to the end of the rotor3 near the pulley 20. The mixed flow fan 11 has two kinds of fan blades:inclined fan blades that incline to a fan base plate 111 and uprightblades. The centrifugal fan 12 is welded to the other end of the rotor3. The centrifugal fan 12 has a fan base plate 121 and upright fanblades extending from the fan base plate 121.

[0034] The housing 4 is composed of a front housing member 4 a and arear housing member 4 b. Each housing member 4 a, 4 b has air-intakewindows 41 disposed at the axial ends and air-discharge windows 42disposed at radially outer peripheral portions opposite first and secondcoil-end groups 31 a, 31 b of the stator 2.

[0035] The rectifier unit 5, which converts ac power generated from thestator 2 to dc power, is disposed at a portion of the ac generator awayfrom the pulley 20.

[0036] The stator 2 functions as an armature. The stator 2 includes astator core 32 that has a plurality of slots 35, a three-phase statorwinding 31 that is composed of a plurality of U-shaped conductorsegments 33 disposed in the slots 35 and insulators 34 that insulate thestator winding 31 from the stator core 32.

[0037] Thirty six slots 35 are circumferentially formed at the innersurface of the stator core 32 at equal intervals so as to accommodatethe three-phase stator winding 3 1. As shown in FIG. 2, four or anothereven number of conductors 331 a, 332 a, 332 b′, 332 a′ are aligned in aradial direction in each slot 35 in four layers: an innermost layer, aninner middle layer, an outer middle layer, and an outermost layer. Theconductor segments 33 are coated with insulation film made ofpolyamideimide.

[0038] The U-shaped conductor segments 33 are connected in a prescribedpattern to form the stator winding 31. Each of the U-shaped conductorsegments 33 have a pair of conductors that are welded at the secondcoil-end group.

[0039] The conductor 331 a of one of the U-shaped conductor segment 33disposed in a first one of the slots 35 is paired with another conductor331 b of the same conductor segment 33 disposed in a second one of theslots 35 that is one pole-pitch spaced apart from the first one of theslots 35. For example, the conductor 331 a disposed in the radiallyinnermost layer of a first slot 35 is paired with the conductor 331 bdisposed in the radially outermost layer of a second slot that is onepole-pitch spaced apart from the slot 35 as shown in FIGS. 2 and 3. Inthe same manner, the conductor 332 a disposed in the radially innermiddle layer of the first slot is paired with the conductor 332 bdisposed in the radially outer middle layer of the second slot 35.Accordingly, a turn portion 331 c of the first conductor segment 33encloses a turn portion 332 c of the second conductor segment 33. Theturn portion 332 c forms a middle-layer coil-end, and the turn portion331 c forms an outer-layer coil-end at an axial end of the stator core22.

[0040] On the other hand, the conductor 332 a projecting from the innermiddle layer of the first slot 35 is welded to a conductor (which is notshown) projecting from the innermost layer of the second slot 35. In thesame manner, a conductor 331 b′ projecting from the outermost layer ofthe first slot 35 is connected to the conductor 332 b that is projectingfrom the outer middle layer of the second slot 35.

[0041] Accordingly, connection ends 332 d, 331 d′ for connecting theconductors 332 a and another respectively disposed in the outer middleand the outermost layers and the connection ends 331 e′, 332 e forconnecting the conductors 331 b′, 332 b respectively disposed in theinnermost and inner middle layers are shifted from each other in thecircumferential direction and disposed at the other axial end of thestator core 32. Thus, inner connection portions that include theconnection ends 332 d, 331 d′ and outer connection portions that includethe connection ends 331 e′ and 232 e form double coaxial rings ofcoil-end layers.

[0042] As shown in FIG. 3, a larger U-shaped conductor segment 331 isprovided with the conductor 331 a disposed in the innermost layer andthe conductor 331 b disposed in the outermost layer, and a smallerU-shaped conductor segments 332 is provided with the conductor 332 adisposed in the inner middle layer and the conductor 332 b disposed inthe outer middle layer. One of the larger U-shaped segments 231 and oneof the smaller U-shaped conductor segments form a basic pair of theU-shaped conductor segments 33. The above described arrangement isrepeated at all the slots 35 of the stator core 22.

[0043] The stator winding 21 is comprised of three phase-windings, eachof which is a two-turn coil formed of a plurality of the basic pairs ofU-shaped conductor segments 33 to be circumferentially mounted in thestator core 32.

[0044] As shown in FIGS. 4 and 5, the conductors of the conductorsegments 33 cross each other at an angle larger than 0 degree. Pairs ofthe conductors are welded together at side surfaces thereof crossingeach other. As shown in FIG. 5, a connection end 331 d of the conductor331 a projecting from the innermost layer of a first slot 35 of thestator core 32 contacts a connection end 332 d of the conductor 332 aprojecting from the inner middle layer of second slot 35 on therespective side surfaces. In the same manner, a connection end 332 e ofa conductor 332 b projecting from the inner middle layer of the firstslot 35 contacts a connection end 331 e of a conductor 331 b projectingfrom the inner middle layer of the second slot 35 on the respective sidesurfaces.

[0045] A method of manufacturing the stator winding 31 will be describedbelow.

[0046] The basic pair of U-shaped conductor segments 33 is arranged sothat the turn portion 331 c of the U-shaped larger segment 331 enclosesthe turn portion 332 c of the U-shaped smaller segment 332 and insertedinto the slots 35 from a position on one axial end of the stator core32. The conductor 331 a of the larger conductor segment 331 is insertedinto the innermost layer of a first one of the slots 35, the conductor332 a of the smaller conductor segment 332 is inserted into the innermiddle layer of the first one of the slots 35, the other conductor 331 bof the larger conductor segment 331 is inserted into the outermost layerof a second one of the slots 35 that is one pole-pitch clockwise shiftedfrom the first one of the slots 35, and the other conductor 332 b of thesmaller conductor segment 332 is inserted into the second one of theslots 35.

[0047] Accordingly, straight portions of the conductors 331 a, 332 a,332 b′, 331 b′ are aligned in a slot, as shown in FIG. 3. Here, theconductors 332 b′ and 331 b′ are conductors of another basic pair ofU-shaped conductor segments that has conductors inserted into anotherslot that is one pole-pitch shifted.

[0048] Thereafter, the straight portion of the conductor 331 aprojecting from the innermost layer of the slot 35 and the straightportion of the conductor 331 b projecting from the outermost layer ofthe slot 35 are bent by a half pole pitch so that each of the connectionends 331 d, 331 e of the larger segment 331 expands over one and a halfpole pitches, at the second coil-end group 31 b. On the other hand, thestraight portion of the conductor 332 a projecting from the inner middlelayer of the slot 35 and the straight portion of the conductor 332 bprojecting from the outer middle layer of the slot 35 are bent by a halfpole pitch so that each of the connection ends 331 d, 331 e of thelarger segment 331 closes. As a result, in the second coil-end group 31b, the conductors that are adjacent to each other respectively inclinein the opposite circumferential directions. Thus, all the conductorsegments are bent in the same manner as described above.

[0049] In the second coil-end group 31 b, the connection end 331 e′ ofthe conductor 331 b projecting from the outermost layer and theconnection end 332 e of the conductor 332 b projecting from the outermiddle layer are welded at their side surfaces by a welder such as aultrasonic welder or an arc welder, or are soldered, as shown in FIG. 4.The conductor segments 33 can be connected in such a manner as shown inFIGS. 12 and 13. That is, the top surface of one conductor segment 33 iswelded to a side surface of another conductor segment 33.

[0050] Thereafter, the conductors 331 a projecting from the innermostlayer of the slots 35 and the conductors 332 b projecting from the outermiddle layer of the slots 35 are bent to incline counterclockwise asviewed from a position above the second coil-end group 31 b in the firstbending step. Then, the conductors 332 a projecting from the innermiddle layer of the slots 35 and the conductors 331 b projecting fromthe outermost layer of the slots 35 are bent to incline clockwise asviewed from a position above the second coil-end group 31 b in thesecond bending step.

[0051] In the first bending step, bending tools 200 are attached to aside surface of the conductors 331 a, 332 b that becomes upside when theconductors 331 a, 332 b are bent, as shown in FIG. 6. Each of the tools200 is turned by a turning device (not shown) counterclockwise about aposition near the open end of the slot 35 so that the connection ends331 d, 332 e move counterclockwise, as shown in FIG. 7.

[0052] In the second bending step, bending tools 202 are attached to aside surface of the conductors 331 a, 332 b that becomes upside when theconductors 332 a, 331 b are bent, as shown in FIG. 8. Each of the tools202 is turned by a turning device (not shown) clockwise about a positionnear the open end of the slot 35 so that the connection ends 332 d, 331e move clockwise, as shown in FIG. 9.

[0053] Therefore, it is not necessary to clamp the connection ends 331d, 331 e, 332 d, 332 e when the conductors 331 a, 331 b, 332 a, 332 bare bent.

[0054] As shown in FIG. 10, the conductor segments 33 are sandwiched bya pair of electrodes, a positive rod electrode 300 disposed radiallyinside of the stator core and a positive rod electrode 302, in a radialdirection of the stator core 32 with a positive rod electrode 304 beingon top of the connection portions, as shown in FIG. 11. The conductorsegments 33 are welded together when a negative rod electrode is broughtnear the connection ends to cause an arc discharge. Thus, an axiallyextending connection end can be omitted.

[0055] In the foregoing description of the present invention, theinvention has been disclosed with reference to specific embodimentsthereof. It will, however, be evident that various modifications andchanges may be made to the specific embodiments of the present inventionwithout departing from the scope of the invention as set forth in theappended claims. Accordingly, the description of the present inventionis to be regarded in an illustrative, rather than a restrictive, sense.

What is claimed is:
 1. A rotary electric machine stator including astator core having a plurality of slots and a stator winding that iscomposed of a plurality of conductor segments, said conductor segmentshaving straight portions disposed in radial layers in said slots andconnection portions projecting from said slots to be welded, whereinsaid connection portions that are welded together cross each other attheir ends.
 2. The rotary electric machine stator as claimed in claim 1,wherein each of said pair of connection ends has a side surface incontact with a side surface of the other connection portion, and saidpair of connection portions is connected together at said side surfaces.3. The rotary electric machine stator as claimed in claim 1, wherein oneof said pair of connection portions has a top surface and the other ofsaid pair of connection portions has a side surface in contact with saidtop surface, and wherein said pair of connection portions is connectedtogether at said side surface in contact with said top surface.
 4. Therotary electric machine stator as claimed in claim 1, wherein one of apair of conductor segments whose connection portions are welded isdisposed adjacent the other conductor segment in a radial direction ofsaid stator and is bent in a circumferential direction of said statorthat is opposite to the other conductor segment.
 5. A rotary electricmachine stator including a stator core having a plurality of slots and astator winding that is composed of a plurality of conductor segments,each of said conductor segments having a straight portion disposed inthe slots and a connection end projecting from said slots and beingwelded to one another, wherein a pair of said connection ends that areconnected together cross each other at an angle larger than zero degree.6. A method of manufacturing a rotary electric machine stator comprisingthe steps of: inserting straight portions of conductor segments into aplurality of slots of a stator core; bending said conductor segments sothat connection ends of said conductor segments that are disposedadjacent to each other in a radial direction can incline in oppositecircumferential directions to cross one another; and welding pairs ofsaid connection ends crossing each other.
 7. The method as claimed inclaim 6, wherein said step of bending comprises a step of attaching abending tool to a side surface of said conductor segments and a step ofturning said bending tool about a position near one of the slots.
 8. Amethod of manufacturing a rotary electric machine stator comprising thesteps of: inserting straight portions of conductor segments into aplurality of slots of a stator core in a plurality of radial layers ineach slot so that end portions of said straight portions project fromthe slots in said radial layers; bending said end portions so that saidend portions in adjacent layers incline in opposite circumferentialdirections to cross one another; and welding said end portions thatcross each other together.
 9. The method as claimed in claim 8, whereinsaid step of bending comprises a step of attaching a bending tool to aside surface of said conductor segments and a step of turning saidbending tool about a position near one of the slots.